title: [Characterizing the passive opening of the eustachian tube in a hypo-/hyperbaric pressure chamber].
abstract: BACKGROUND
  Beside arbitrary and not arbitrary active pressure equalization systems there is a passive equalization system via the Eustachian tube (ET) at pressure difference between the epipharyngeal space and the middle ear. Aim of this study was to characterize this passive equalization system in a hypobaric/hyperbaric pressure chamber by continuously measuring the tympanic impedance. In contrast to other studies, which are measured only in a hypobaric pressure chamber it is possible to include participants with Eustachian tube dysfunction (ETD).
  
  
  METHODS
  Following a fixed pressure profile 39 participants were exposed to phases of pressure rising and decompression. By continuously measuring the tympanic impedance in the pressure chamber it was possible to measure data of the Eustachian Tube opening Pressure (ETOP), Eustachian Tube closing pressure (ETCP) and Eustachian Tube opening duration (ETOD). In addition it was possible to characterize the gradient of pressure during decompression, while the ET was open.
  
  
  RESULTS
  Beside the measurement of the arithmetic average of the ETOP (30.2 ± 15.1 mbar), ETCP (9.1 ± 7.7 mbar) and ETOD (0.65 ± 0.38 s) it was obvious that there are recurrent samples of pressure progression during the phase of tube opening. Generally it is possible to differentiate between the type of complete opening and partial opening.
  
  
  CONCLUSIONS
  The fundamental characterization of the action of the passive tube opening, including the measurement of the ETOP, ETCP and ETOD, is a first step in understanding the physiological and pathophysiological function of the ET.
authors.affiliation: Klinik und Poliklinik für Hals-Nasen-Ohrenheilkunde, Kopf- und Hals-Chirurgie, Uniklinik Köln, Germany. moritz.meyer@uk-koeln.de
authors.forename: M F
authors.initials: MF
authors.lastname: Meyer
authors.forename: S
authors.initials: S
authors.lastname: Mikolajczak
authors.forename: J C
authors.initials: JC
authors.lastname: Luers
authors.forename: S
authors.initials: S
authors.lastname: Lotfipour
authors.forename: D
authors.initials: D
authors.lastname: Beutner
authors.forename: M D
authors.initials: MD
authors.lastname: Jumah
mesh_terms: D000158:Acoustic Impedance Tests; D000328:Adult; D001273:Atmosphere Exposure Chambers; D001274:Atmospheric Pressure; D004432:Ear, Middle / Q000502:physiology; D005064:Eustachian Tube / Q000502:physiology*; D006801:Humans; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012016:Reference Values